Allow passing the currently active kitty window id in the launch command

See #2391

docs/changelog.rst

@@ -26,6 +26,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - X11: Fix arrow mouse cursor using right pointing instead of the default left
   pointing arrow (:iss:`2341`)
 
+- Allow passing the currently active kitty window id in the launch command
+  (:iss:`2391`)
+
 - unicode input kitten: Allow pressing :kbd:`ctrl+tab` to change the input mode
   (:iss:`2343`)
 

docs/launch.rst

@@ -50,6 +50,17 @@ being the top left corner and ``{lines},{columns}`` being the number of rows
 and columns of the screen.
 
 
+Special arguments
+-------------------
+
+There are a few special placeholder arguments that can be specified as part of
+the command line. Namely ``@selection`` which is replaced by the current
+selection and ``@kitty_active_window_id`` which is replaced by the id of the
+currently active kitty window. For example::
+
+    map f1 launch my-program @kitty-active-window-id
+
+
 Syntax reference
 ------------------